• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2001년도 Proceedings of 2001 International Symposium
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• pp.141-145
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• 2001

Isopentenyl diphosphate (IPP) is the common, five-carbon building block in the biosynthesis of all carotenoids. IPP in Escherichia coli is synthesized through the non-mevalonate pathway. The first reaction of IPP biosynthesis in E. coli is the formation of l-deoxy-D-xylulose-5-phosphate (DXP), catalyzed by DXP synthase and encoded by dxs. The second reaction in the pathway is the reduction of DXP to 2-C-methyl-D-erythritol-4-phosphate, catalyzed by DXP reductoisomerase and encoded by dxr. To determine if one or more of the reactions in the non-mevalonate pathway controlled flux to IPP, dxs and dxr were placed on several expression vectors under the control of three different promoters and transformed into three E. coli strains (DH5$\alpha$, XL1-Blue, and JMl0l) that had been engineered to produce lycopene. Lycopene production was improved significantly in strains transformed with the dxs expression vectors. When the dxs gene was expressed from the arabinose-inducible araBAD promoter ( $P_{BAD}$) on a medium-copy plasmid, lycopene production was 2-fold higher than when dxs was expressed from the IPTG-inducible trc and lac promoters ( $P_{trc}$ and $P_{lac}$, respectively) on medium-copy and high-copy plasmids. Given the low final densities of cells expressing dxs from IPTG-inducible promoters, the low lycopene production was probably due to the metabolic burden of plasmid maintenance and an excessive drain of central metabolic intermediates. At arabinose concentrations between 0 and 1.33 roM, cells expressing both dxs and dxr from $P_{BAD}$ on a medium-copy plasmid produced 1.4 - 2.0 times more lycopene than cells expressing dxs only. However, at higher arabinose concentrations lycopene . production in cells expressing both dxs and dxr was lower than in cells expressing dxs only. A comparison of the three E. coli strains transformed with the arabinose-inducible dxs on a medium-copy plasmid revealed that lycopene production was highest in XLI-Blue.LI-Blue.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2005년도 2005 Annual Meeting & International Symposium
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• pp.245-247
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• 2005

A cellulolytic fungus isolated from Agave plantation in northeastern Thailand was identified as Acrophialophora nainiana. The fungus was capable of growing at pH between 3 - 7 and 25 - 45 $^{\circ}C$, with the optimum conditions at pH 5.0 and 40 $^{\circ}C$. The wild isolate produced cellulases, comprising of exoglucanase (0.019 U/mg protein), endoglucanase (0.366 U/mg protein), and ${\beta}$-glucosidase (0.001 U/mg protein). Mutations with UV and NTG produced the UV 10-2 mutant with cellulases activities including exoglucanase (0.093 U/mg protein), endoglucanase (0.585 U/mg protein), and ${\beta}$-glucosidase (0.013 U/mg protein). Purification of the enzymes with ultrafiltration, ammonium sulfate precipitation, and ion-exchange chromatography yielded the maximal cellulase specific activities of 2.736 U/mg protein (exoglucanase), 0.235 U/mg protein (endoglucanase), and 0.008 U/mg protein (${\beta}$-glucosidase). The mutant's cellulases were the most active at pH 5.0 and 60 $^{\circ}C$. Ion-exchange chromatography revealed that A. nainiana UV 10-2 cellulases were comprised of two peaks with one peak showing the single endoglucanase activity while the other peak showed a mixture of the three enzyme activities. Production of A. nainiana UV 10-2 cellulases using banana leaf stalk as the sole carbon source gave comparable yields to that of the pure ${\alpha}$-cellulose. The enzymes were used in the simultaneous saccharification and fermentation (SSF) of plant residue (Coix aquatica) along with Kluveromyces marxianus to produce ethanol. Moreover, when the enzymes were used in the bioscouring process of fabric, the desiravle traits of textile processing including immediate water absorbency, increased in whiteness and reduction of yellowness of the treated fabric were observed.

• Tribology and Lubricants
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• 제35권5호
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• pp.274-285
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• 2019

Chemical mechanical polishing (CMP), which is a material removal process involving chemical surface reactions and mechanical abrasive action, is an essential manufacturing process for obtaining high-quality semiconductor surfaces with ultrahigh precision features. Recent rapid growth in the industries of digital devices and semiconductors has accelerated the demands for processing of various substrate and film materials. In addition, to solve many issues and challenges related to high integration such as micro-defects, non-uniformity, and post-process cleaning, it has become increasingly necessary to approach and understand the processing mechanisms for various substrate materials and abrasive particle behaviors from a tribological point of view. Based on these backgrounds, we review recent CMP R&D trends in this study. We examine experimental and analytical studies with a focus on substrate materials and abrasive particles. For the reduction of micro-scratch generation, understanding the correlation between friction and the generation mechanism by abrasive particle behaviors is critical. Furthermore, the contact stiffness at the wafer-particle (slurry)-pad interface should be carefully considered. Regarding substrate materials, recent research trends and technologies have been introduced that focus on sapphire (${\alpha}$-alumina, $Al_2O_3$), silicon carbide (SiC), and gallium nitride (GaN), which are used for organic light emitting devices. High-speed processing technology that does not generate surface defects should be developed for low-cost production of various substrates. For this purpose, effective methods for reducing and removing surface residues and deformed layers should be explored through tribological approaches. Finally, we present future challenges and issues related to the CMP process from a tribological perspective.

• 반도체디스플레이기술학회지
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• 제9권3호
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• pp.53-58
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• 2010

In this study, we have investigated the effect of the ambient gases on the characteristics of IZO thin films for the OLED (organic light emitting diodes) devices. For this purpose, IZO thin films were deposited by RF magnetron sputtering under various ambient gases (Ar, $Ar+O_2$ and $Ar+H_2$) at $150^{\circ}C$. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon mixing gas has been changed from 0.1sccm to 0.5sccm, respectively. All the samples show amorphous structure regardless of ambient gases. The electrical resistivity of IZO film increased with increasing flow rate of $O_2$ under $Ar+O_2$ while under $Ar+H_2$ atmosphere the electrical resistivity showed minimum value near 0.5sccm of $H_2$. All the films showed the average transmittance over 85% in the visible range. The OLED device was fabricated with different IZO substrates made by configuration of IZO/${\alpha}$-NPD/DPVB/$Alq_3$/LiF/Al to elucidate the performance of IZO substrate. OLED devices with the amorphous-IZO (a-IZO) anode film show better current densityvoltage-luminance characteristics than that of OLED devices with the commercial crystalline-ITO (c-ITO) anode film. It can be explained that very flat surface roughness and high work function of a-IZO anode film lead to more efficient hole injection by reduction of interface barrier height between anode and organic layers. This suggests that a-IZO film is a promising anode materials substituting conventional c-ITO anode in OLED devices.

• Archives of Pharmacal Research
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• 제24권6호
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• pp.568-571
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• 2001

The purpose of this work was to study the effect of storage time and temperature on the in vitro release kinetics of a commercial sustained-release dosage form of theophylline, at different pHs of the dissolution medium. The formulation was stored at $35^{\circ}C$ for 16 months and at $45^{\circ}C$ for 8 months, with a relative humidity of 60%. The in vitro release tests were performed at pHs 2, 4, 6 and 7.4. The mean values of the transport coefficient n, were close to 0.5 in all the conditions tested, which indicates that the transport system is not modified after storage of the formulation at $35^{\circ}C$ and $45^{\circ}C$. The mean values of the dissolution rate constant ranged from 0.036 to 0.043 $min^{-n}$, under all the conditions tested. Significant differences (${\alpha}=0.05$) were found between pHs 2, 4 and 6, 7.4 for all the model-independent parameters studied. When the formulation was kept at $35^{\circ}C$ for 16 months, the mean percentage of drug dissolved at 8 hours was 25.61% (pHs 2, 4) and, 36.12% (pHs 6, 7.4), representing a 26% and 24% reduction, respectively. Simitar results were obtained after storing the formulation at $45^{\circ}C$ for 8 months, corresponding to 33.3% (pHs 2, 4) and, 22.5% (pHs 6, 7.4) diminution, respectively. The values of the similarity factory $f_2$, obtained were lower than 50, which indicates the lack of similarity among the dissolution profiles, after storing the formulation under the experimental Conditions tested.

• 대한본초학회지
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• 제32권2호
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• pp.65-75
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• 2017

Objectives : This study aimed to evaluate the protective effect of Orostachydis Herba (OH) and Fermented OH (OHF) against the acute liver injury by lipopolysaccharide (LPS). Methods : OHF by 4 lactic bacteria such as (Lactobacillus hilgardii (OHF1), Leuconostoc mesenteroides (OHF2), Pediococcus acidilactici (OHF3), Saccharomyces cerevisiae (OHF4)) were prepared. Samples were selected to OHF0, OHF2, OHF3 based on UPLC analysis, DPPH, ABTS radical scavenging activities. To evaluate the protective effect of OHF on liver injury mice, ICR mice were divided into 5 groups: Normal mice (Nor), LPS (20 mg/kg) treated mice (Veh), administrated OHF0, OHF2 OHF3 200 mg/kg body weight during 8 days before LPS injection. Serum and liver were collected 24 hours after LPS injection. Results : The activity was high in order of OHF0 and OHF3 in DPPH and ABTS radical scavenging activities. The quercetin contents for bioactive ingredient of OH was 5.39, kaempferol contents was 9.94 by UPLC analysis. The LPS-treated vehicle group significantly increased liver weight, and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in serum. In contrast, administrated OHF3 group decreased liver weight, AST, ALT. In addition, OHF3 groups reduced the elevated levels of reactive oxygen species (ROS) in serum and tissues. Moreover, AP-1, iNOS and COX-2 were significantly decreased in OHF2 and OHF3. But $NF-{\kappa}B$ p65 and $TNF-{\alpha}$ only showed a significant reduction in OHF3. Conclusions : Therefore, these results suggest that fermented Orostachydis Herba might be protective effect on liver injury through anti-oxidant effect.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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• pp.621-633
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• 2023

We investigated the probiotic characteristics and anti-obesity effect of Lactiplantibacillus plantarum MGEL20154, a strain that possesses excellent intestinal adhesion and viability. The in vitro properties, e.g., gastrointestinal (GI) resistance, adhesion, and enzyme activity, demonstrated that MGEL20154 is a potential probiotic candidate. Oral administration of MGEL20154 to diet-induced obese C57BL/6J mice for 8 weeks resulted in a feed efficacy decrease by 44.7% compared to that of the high-fat diet (HFD) group. The reduction rate of weight gain was about 48.5% in the HFD+MGEL20154 group compared to that of the HFD group after 8 weeks, and the epididymal fat pad was also reduced in size by 25.2%. In addition, the upregulation of the zo-1, pparα, and erk2, and downregulation of the nf-κb and glut2 genes in Caco-2 cells by MGEL20154 were observed. Therefore, we propose that the anti-obesity effect of the strain is exerted by inhibiting carbohydrate absorption and regulating gene expression in the intestine.

• 한국자기학회지
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• 제6권3호
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• pp.151-157
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• 1996

반응가스의 분압과 압력비($P_{CH4}/P_{CH4}+P_{N2}$)가 FeTaNC 박막의 연자기특성에 미치는 영향을 조사하였다. 반응가스분압 5%에서 가장 우수한 연자기특성을 나타내었는데 포화자속밀도는 $N_{2}$ 가스와 $CH_{4}$ 가스가 혼합($P_{CH4}$ : 20%~100%)된 조성에서 15~17 kG의 높은 값을 나타내었으며 보자력과 투자율(5 MHz)도 각각 0.3~0.5 Oe, 2000~4000의 값을 나타내었다. 또한, 반응가스분압 10%에서도 $P_{CH4}$이 30%에서 100%로 조성이 변함에 따라 포화자속밀도 15 kG, 보자력 0.18~0.4 Oe, 투자율(5 MHz) 2000~4000의 우수한 연자기 특성을 얻을 수 있었다. 반응가스분압 15%에서 포화자속밀도는 15 kG 정도로 일정하였으나 보자력과 투자율 (5 MHz)은 ($P_{CH4}/P_{CH4}+P_{N2}$) < 0.5 구간에서 보자력 > 0.5 Oe, 투자율(5 MHz) < 1000,($P_{CH4}/P_{CH4}+P_{N2}$) > 0.5 구간에서 보자력 < 0.5 Oe, 투자율(5 MHz) > 1000을 나타내었다. 반면 반응가스분압 20%에서는 과다한 반응가스 첨가에 의해 높은 보자력과 낮은 투자율을 나타내어 연자기특성을 얻을 수 없었다. 따라서 Ta 8%의 조성에서 반응가스분압이 20%에서 5%로 감소할수록 연자기특성이 크게 향상된 것으로 고찰되었다.

• 생명과학회지
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• 제26권12호
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• pp.1376-1382
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• 2016

Xylitol은 식품 및 의료산업에서 이용가치가 높은 물질로, lignocellulosic biomass인 xylose의 환원으로부터 생산되며, 대부분 유전적으로 안전한 Saccharomyces cerevisiae 균주를 사용하여 생산되고 있다. 따라서 본 연구에서는 S. cerevisiae에서 xylitol을 효율적으로 생산하기 위해 xylose reductase를 code하는 GRE3 (YHT104W)유전자의 발현시스템을 구축하여, xylose reductase의 분비생산 및 xylitol 생산성을 조사하고자 하였다. 먼저 GRE3 유전자의 발현에 적합한 promoter의 선별을 위해 GAL10 promoter와 ADH1 promoter 하류에 각각 mating factor ${\alpha}$ ($MF{\alpha}$) signal sequence와 GRE3 유전자를 가진 pGMF-GRE3와 pAMF-GRE3 plasmid를 구축하였다. 각각의 plasmid는 S. cerevisiae $SEY2102{\Delta}trp1$균주에 형질전환되었고, $SEY2102{\Delta}trp1$/pGMF-GRE3와 $SEY2102{\Delta}trp1$/pAMF-GRE3 형질전환주가 선별되었다. 그 중 $SEY2102{\Delta}trp1$/pGMF-GRE3 균주에서 NADPH를 cofactor로 사용했을 때 0.34 unit/mg-protein의 xylose reductase 활성(total activity)을 보였고, ADH1 promoter를 가진 $SEY2102{\Delta}trp1$/pAMF-GRE3 균주에 비해 1.5배 높은 활성증가를 확인 할 수 있었다. 또한 두 균주에서 모두 91%의 분비효율을 보여 대부분의 재조합 xylose reductase가 세포 밖으로 효율적으로 발현 분비되었음을 알 수 있었다. $SEY2102{\Delta}trp1$/pGMF-GRE3 균주를 사용한 baffled flask 배양에서 xylitol 생산량을 조사해 본 결과, 20 g/l의 xylose로부터 12.1 g/l의 xylitol을 생산하였고, 소모된 xylose의 약 83%정도가 xylitol로 환원되었음을 알 수 있었다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제11권1호
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• pp.28-35
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• 2008

목 적: 종양 괴사 인자(TNF-${\alpha}$)에 대한 단 클론 항체인 infliximab으로 소아의 난치성 크론병에서의 치료와 관해 유도 치료제로서의 효과에 대한 치료 경험을 보고 하고자 한다. 방 법: 2001년 3월부터 2007년 8월까지 삼성서울병원에서 크론병으로 진단 받은 소아 청소년 중 기존 약제에 관해 유도되지 않는 불응성 크론병(스테로이드 의존성 포함)과 중증 활성 크론병을 가진 16명에서 infliximab (Remicade$^{(R)}$) 5 mg/kg를 관해 유도(0, 2, 8주) 주입하였으며 필요한 경우 8주 간격의 유지 치료를 시행하였고 누공성 크론병의 경우 누공의 상태에 따라 비정기적으로 주입하였다. 대상 환자들의 특징 및 치료 전 후의 질병 활성도, Hct, ESR, CRP, albumin을 paired t test를 이용하여 비교하였다. 결 과: 16명의 남녀비는 13/3이고 중앙 연령은 13세 (21개월~15세)였다. 투여 적응증은 불응성 크론병 7명(스테로이드 의존성 3명 포함), 중증 활성형 크론병의 관해 유도 7명, 누공성 크론병 2명이었다. Infliximab 투여 횟수는 평균 5.19${\pm}$3.41회(3~15회)였고 크론병 진단 후 infliximab 치료 시행까지의 기간 중앙값은 6.5개월(1개월~54개월)이었다. 환자들의 infliximab 투여 전PCDAI (pediatric crohn disease activity index)는 평균 34.19${\pm}$14.96이었으며 마지막 투여 후 2~4주 이내 PCDAI는 6.88${\pm}$10.31로 투여 후 통계적으로 유의한 호전을 보였다(p=0.000). 다른 혈액학적 표지자로 ESR (p=0.000), serum albumin (p=0.016), CRP (p=0.009)가 투여 전후로 의미 있는 호전을 보였으며 적혈구 용적률 (hematocrit)의 호전은 통계적으로 유의하지 않았다(p=0.075). 고식적인 치료에 관해 유도 되지 않았던 난치성 환자 4명 중 2명에서 관해 유도가 가능하였으며 스테로이드 의존성 환자 3명 중 2명에서 스테로이드 중단 1명에서 스테로이드 감량이 가능하였다. 누공이 동반되거나 중등도 이상의 크론병에서 스테로이드를 포함하는 다른 면역 조절제 사용 전에 top-down 요법을 시행한 7명 모두에서 6주 이내에 관해가 되었다. 난치성 누공 치료에서도 10명 중 9명에서 호전되었다. 결 론: Infliximab을 사용하여 소아 불응성 크론병에서 관해 유도와 유지 및 스테로이드 감량 또는 중단이 가능하였으며 중등도 이상의 크론병에서 top-down 관해 요법으로도 비교적 효과적이었다. 앞으로 장기간의 추적 관찰을 통한 효과 판정 및 부작용 관찰을 요한다.